Novel photographic products and processes

ABSTRACT

The present invention is directed to a photographic film unit adapted to provide, by diffusion transfer processing, selective dye image recordation of incident actinic radiation as a function of the point-to-point degree of photosensitive element exposure, which film unit includes a plurality of layers including a photosensitive silver halide layer having associated therewith diffusion transfer process dye image-forming material; and a silver halide developing agent selected from the group consisting of 2,6-di-t-butyl hydroquinone; 2,5-di-t-butyl hydroquinone; durohydroquinone; and the precursors thereof, and a layer adapted to receive dye image-forming material diffusing thereto; and to specified diffusion transfer processes employing such film units.

United States Patent [191 Charkoudian [451 June 11, 1974 1 NOVELPHOTOGRAPHIC PRODUCTS AND 211 Appl. No.: 287,629

[52] US. Cl 96/3, 96/29 D, 96/66 R, 96/76 R, 96/77 [51] Int. Cl. G03c7/00, G030 5/54, G03c 5/30, G03c l/48, G03c l/40 [58] Field of Search96/3, 76 R, 95 R, 77, 66 R,

OTHER PUBLICATIONS Lee and James, Superadditivity in PhotographicDevelopment by Substituted Hydroquinones Used with Phenidone, Photo.Science and Engrg, Vol. 6, No. 1, Jan.-Feb. 1962, pp. 32-38.

Primary Examiner-Ronald H. Smith Assistant Examiner-Richard L. Schilling[5 7] ABSTRACT The present invention is directed to a photographic filmunit adapted to provide, by diffusion transfer processing, selective dyeimage recordation of incident actinic radiation as a function of thepoint-to-point degree of photosensitive element exposure, which filmunit includes a plurality of layers including a photosensitive silverhalide layer having associated therewith diffusion transfer process dyeimage-forming material; and a silver halide developing agent selectedfrom the group consisting of 2,6-di-t-buty1 hydroquinone; 2,5-di-t-butylhydroquinone; durohydroquinone; and the precursors thereof, and a layeradapted to receive dye image-forming material diffusing thereto; and tospecified diffusion transfer processes employing such film units.

22 Claims, 7 Drawing Figures NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSESBACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention is directed to providing new and improved diffusion transferprocess photographic film units adapted to provide, as a function of thepointto-point degree of photoexposure, by diffusion transfer processinga dye transfer image.

2. Description of Prior Art As disclosed in U.S. Pat. No. 3,415,644, acomposite photosensitive structure, particularly adapted for reflectiontype photographic diffusion transfer color process employment, whichcomprises a plurality of essential layers including, in sequence, adimensionally stable opaque layer; one or more silver halide emulsionlayers having associated therewith dye image-providing material which issoluble and diffusible, in alkali, at a first pH, as a function of thepoint-to-point degree of its associated silver halide emulsion .sexposure to incident actinic radiation; a polymeric layer adapted toreceive solubilized dye image-providing material diffusing thereto; apolymeric layer containing sufficient acidifying capacity to effectreduction of a processing composition from the first pH to a second pHat which the dye image-providing material is substantiallynondiffusible; and a dimensionally stable transparent layer, may beexposed to incident actinic radiation and processed by interposing,intermediate the silver halide emulsion layer and the reception layer,an alkaline processing composition possessing the first pH andcontaining opacifying agent, which may reflect incident radiation, in aquantity sufficient to mask dye image-providing material associated withthe silver halide emulsion.

In a preferred embodiment, the composite photosensitive structureincludes a rupturable container, retaining the alkaline processingcomposition having the first pH and opacifying agent, fixedly positionedextending transverse a leading edge of the composite structure in orderto effect, upon application of compressive pressure to the container,discharge of the processing composition intermediate the opposedsurfaces of the reception layer and the next adjacent silver halideemulsion.

The liquid processing composition, distributed intermediate thereception layer and the silver halide emulsion, permeates the silverhalide emulsion layers of the composite photosensitive structure toinitiate development of the latent images contained therein resultantfrom photoexposure. As a consequence of the development of the latentimages, dye image-providing material associated with each of therespective silver halide emulsion layers is individually mobilized as afunction of the point-to-point degree of the respective silver halideemulsion layers photoexposure, resulting in imagewise distributions ofmobile dye image-providing materials adapted to transfer, by diffusion,to the reception layer to provide the desired transfer dye image.Subsequent to substantial dye image formation in the reception layer, asufficient portion of the ions of the alkaline processing compositiontransfers, by diffusion, to the polymeric neutralizing layer to effectreduction in the alkalinity of the composite film unit to the second pHat which dye image-providing material is substantially 2 nondiffusible,and further dye image-providing material transfer is therebysubstantially obviated.

The transfer dye image is viewed, as a reflection image, through thedimensionally stable transparent layer against the background providedby the opacifying agent, distributed as a component of the processingcomposition, intermediate the reception layer and next adjacent silverhalide emulsion layer. The thus-formed opacifying stratum efiectivelymasks residual dye image-providing material retained in association withthe silver halide emulsion layer subsequent to processing.

In U.S. Pat. No. 3,415,646, the dimensionally stable layer of the filmunit next adjacent the photosensitive silver halide layer or layers isdisclosed to be transparent to incident actinic radiation and asdisclosed in U.S. Pat. No. 3,415,645, in such instance the opacifyingagent may be initially disposed in the film unit interme diate thereception layer and next adjacent silver halide layer.

As disclosed in U.S. Pat. No. 3,615,421 of Edwin H.

Land, issued Oct. 26, 1971, and the copending U.S. patent applicationSer. No. 3,646 of Sheldon A. Buckler, filed Jan. 19, 1970, now U.S. Pat.No. 3,661,585 issued May 9, 1972, the opacifying component of the filmunit may optionally be initially disposed as a preformed processingcomposition penneable layer, intermediate the reception layer and nextadjacent silver halide layer, in a concentration which prior tophotoexposure is insufficient to prevent transmission therethrough ofexposing actinic radiation and which, subsequent to processing,possesses an opacifying capacity effective to mask residual dyeimage-providing material retained associated with the film units silverhalide emulsion layers, and in the copending U.S. patent applicationSer. No. 43,742 of Edwin H. Land, filed June 5, 1970, now U.S. Pat. No.3,647,435 issued Mar. 7, 1972 the opacifying component of the film unitmay optionally be initially formed in situ, intermediate the receptionlayer and next adjacent silver halide layer, during photographicprocessing of the film unit.

In the copending U.S. patent applications of Edwin H. Land, Ser. No.786,352, filed Dec. 23, 1968, and Ser. No. 43,782, filed June 5, 1970,the opacifying component is disclosed to optionally comprise alightabsorbing reagent such as a dye which is present as an absorbingspecies at the first pH and which may be converted to a substantiallynon-absorbing species at the second pH, and in U.S.. Pat. Nos. 3,473,925and 3,573,042 and the U.S. Pat. of Terry W. Milligan and Richard W.Young, No. 3,576,626 issued Apr. 27, 1971, opacifying and reflectingcomponent, respectively, may be individually interposed intermediate thesilver halide layer and reception layer by selective distribution from acomposite or a plurality of rupturable containers.

In U.S. Pat. No. 3,573,043, the polymeric neutralizing layer isdisclosed to be optionally disposed intermediate the dimensionallystableopaque layer and next adjacent essential layer, i.e., next adjacentsilver halide/dye image-providing material component, to effect thedesignated modulation of film units environmental pH; the U.S. Pat. No.3,576,625 of Edwin H. Land, issued Apr. 27, 1971, discloses theemployment of particulate acid distributed within the film unit toeffect the modulation of the environmental pH, and U.S. Pat. No.3,573,044 discloses the employment of processing composition solventvapor transmissive dimensionally stable layers to effect processmodulation of dye transfer as a function of solvent concentration.

Where desired, the film unit may also be constructed in accordance withthe disclosure of US. Pat. No. 3,594,165 issued July 20, 1971, to HowardG. Rogers and US. Pat. No. 3,594,164 issued July 20, 1971, to Howard G.Rogers to comprise a composite photosensitive structure including atransparent dimensionally stable layer carrying a reception layer, aprocessing composition permeable opaque layer and a photosensitivesilver halide layer and the film unit may include a separatedimensionally stable sheet element adapted to be superposed on thesurface of the photosensitive structure opposite the dimensionallystable layer and may further include means such as arupturable'container retaining processing composition for distributionof a processing composition intermediate the sheet and photosensitivestructure to effect processing. As further disclosed in the last-citedapplications, in structures wherein the receptor is positioned nextadjacent the transparent layer or the processing composition and/or thesheet is to be separated from the remainder of the film unit subsequentto processing, the latter elements may optionally include opacifyingcomponent.

As disclosed in the US. Pat. No. 3,620,724 issued Nov. 16, 1971, toEdwin H. Land, the dimensionally stable layer referred to may be opaqueand in which instance the photosensitive silver halide layer ispositioned next adjacent the opaque support layer and the opacifyingcomponent of the film units processing composition permeable opaquelayer will be disposed in the unit in a concentration insufficient toprevent transmission therethrough of exposing actinic radiation andwhich, subsequent to processing, possesses an opacifying capacityeffective to mask residual dye image-providing material retainedassociated with the silver halide layer, and as disclosed in thecopending US. Pat. application Ser. No. 43,741 of Edwin H. Land, filedJune 5, 1970, now U.S. Pat. No. 3,647,434 issued Mar. 7, 1972, theopacifying agent may be optionally formed in such film unit, in situ,during processing of the unit.

US. Pat. No. 2,983,606 also discloses the employment of a combination ofa dye developer and one or more silver halide developing agents whichare not dye developers, which may act to accelerate or initiatedevelopment. Such added developing agents are referred to as anauxiliary or cooperative developing agent. The auxiliary developingagents provide cleaner highlights and better intermediate tones. Theauxiliary developing agent may be disposed in the processing compositionor one or more layers of the photosensitive element, e.g., in the silverhalide emulsion layer or in the layer containing the dye developer.

The present invention is directed to film units processed with a novelclass of auxiliary developers.

SUMMARY OF THE INVENTION The present invention is directed to a new andimproved, preferably integral negative/positive, diffusion transferprocess photographic film unit adapted to provide, by diffusion transferprocessing, photographic color image reproduction as a function ofexposure of such film unit to incident actinic radiation.

The film unit assemblage construction to be employed in the practice ofthe present invention preferably comprises a film unit of the generaltype set forth in aforementioned US. Pat. Nos. 3,415,644; 3,415,645; and3,415,646; 3,473,925; 3,573,042; 3,573,043; 3,573,044; and copending US.Patent applications Ser. Nos. 786,352; 3,691; 43,741; 43,742; and 43,782and also in US. Pat. Nos. 3,615,421; 3,576,625; 3,576,626; 3,620,724;3,594,165; 3,594,164; 2,983,606; and 3,345,163; and will include one ormore photosensitive silver halide layers having associated therewith dyeimage-forming material which is processing composition diffusible as afunction of the point-to-point degree of silver halide layer exposure toincident actinic radiation; and an auxiliary developing agent selectedfrom the group consisting of 2,6-di-tbutyl hydroquinone; 2,5-di-ti-butylhydroquinone; durohydroquinone; and the precursors thereof, e.g., thealkyl esters, preferably the haloalkyl esters thereof; a layer adaptedto receive image-forming material diffusion thereto; a dimensionallystable layer transparent to incident actinic radiation; and means forinterposing, intermediate the silver halide layers and the receptionlayer, opacifying agent and a processing composition, and, in aparticularly preferred embodiment, a processing composition possessing afirst pH at which the dye image-forming material is diffusible duringprocessing and means'for modulating the pH of the film unit from thefirst pH to a second pH at which the dye imageforming material issubstantially non-diffusible subsequent to substantial dye transferimage formation.

In accordance with a specifically preferred embodiment of the presentinvention, a film unit assemblage of the aforementioned generalstructural parameters will be adapted to be processed, subsequent tophotoexposure, in the presence of actinic radiation and may befabricated to employ, as means interposed intermediate the receptionlayer and next adjacent silver halide layer subsequent to photoexposure,an inorganic lightreflecting pigment dispersion containing reflectingpigment and at'least one optical filter agent, at a pH above the pKa ofthe optical filter agent and at which pH the dye image-forming materialis diffusible during processing as a function of silver halide layerphotoexposure, in a concentration in admixture effective to provide abarrier to transmission of actinic radiation therethrough, and the meansfor interposing the opacifying agent and the processing composition maycomprise a rupturable container, retaining the opacifying agent disposedin the processing composition selected, fixedly positioned extendingtransverse a leading edge of the film unit and adapted, upon applicationof compressive pressure, to distribute its contents intermediate thereception layer and next adjacent silver halide layer.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of aphotographic film unit embodying the invention;

FIGS. 2, 4 and 6 are diagrammatic enlarged crosssectional views of thefilm unit of FIG. 1, along section line 22, illustrating the associationof elements during the three illustrated stages of the performance of adiffusion transfer process, for the production of a multicolor transferimage according to the invention, the thickness of the various materialsbeing exaggerated, and wherein FIG. 2 represents an exposure stage, FIG.4 represents a processing stage and FIG. 6 represents a product of theprocess; and

FIGS. 3, 5 and 7 are diagrammatic, further enlarged cross-sectionalviews of the film unit of FIGS. 2, 4 and 6, along section lines 33, 5-5and 7-7, respectively, further illustrating, in detail, the arrangementof layers comprising the photosensitive laminate during the threeillustrated stages of the transfer process.

DETAILED DESCRIPTION OF THE INVENTION As previously characterized,diffusion transfer photographic processing may be employed to provide apositive reflection dye image, as a direct function of actinic radiationincident on a film unit assemblage which unit is preferably constructedto comprise a plurality of sequential layers including a dimensionallystable layer most preferably opaque to incident radiation; aphotosensitive silver halide layer having associatedtherewith dyeimage-forming material which is processing composition diffusible at aselected first pH as a function of the point-to-point degree of silverhalide layer photoexposure; a layer adapted to receive dye image-formingmaterial diffusing thereto; a dimensionally stable layer transparent toincident radiation; means for interposing, intermediate the silverhalide layer and the reception layer, opacifying agent and preferably aninorganic reflecting pigment dispersion containing at least one opticalfilter agent or dye in a concentration effective to provide, subsequentto selective photoexposure of the silver halide layer, protection of thesilver halide layer from further exposure to actinic radiation incidenton the dimensionally stable layer; and means for converting the pH ofthe film unit from the first pH to a second pH at which the dyeimage-forming material is substantially nondiffusible subsequent tosubstantial dye image-forming material diffusion to the reception layer.

It now has been discovered, however, that a speed increase, in someinstances two stops or more, is achieved by effecting development of afilm unit which comprises a plurality of layers including aphotosensitive layer comprising photosensitive silver halide grainshaving associated therewith dye image-forming material, preferably a dyedeveloper, in the presence of at least one of 2,6-di-t-butylhydroquinone; 2,5-di-t-butyl hydroquinone; durohydroquinone; or thealkyl esters thereof, as an auxiliary developer.

While not intending to be bound by theory, it is believed that theauxiliary developers of the presentinvention, by giving up one electron,fonn extremely unreactive semiquinones; i.e., they will not readilyreduce silver. The loss of the first electron is relatively rapid. Theloss of the second electron results in the formation of a quinone which,as a result of steric hindrance is not subject to nucleophilic attack byother reactants in the system. The-first electron which is releasedimmediately results in relatively nondiscriminatory development bringingthe exposed grains to a catalytic state which renders them more easilydevelopable by the dye developer. The unexposed grains, while developedto some degree by the auxiliary developer, are not sufficiently reducedto provide measurable interaction with the dye developers.

As with the auxiliary developers set forth in US. Pat. No. 2,983,606,the auxiliary developers of thepresent invention may be contained in theprocessing composition or in one or more layers of the photosensitiveelement, e.g., in the silver halide emulsion layer or the layer eontaining the dye image-forming material. In

some instances, it may be desirable to have a portion of the auxiliarydeveloping agent in the processing composition and a portion in thephotosensitive ele ment. When the auxiliary developer is contained inthe processing composition, it is present at a level of about 0004-0008mg./gm. silver. When employed in the emulsion or adjacent layers thelevels are about 0.2 to 5.0 mg./ft. The specific amounts employed willvary with a given photographic film unit depending upon the othercomponents of the film unit and the possible interaction between theauxiliary developers and said components.

As stated above, the auxiliary developers may be disposed at variouslocations in the film unit. However, when the auxiliary developer isdisposed in the photosensitive element, certain reagents or componentssuch as sensitizing dyes and the like undergo deleterious reactions withthe developer, detracting from the usefulness of the film unit, or evenrendering the film unit useless, as by the formation of an excess offog.

By employing the aforementioned precursor, the auxiliary developer, inan inert form, can be disposed in the film unit in substantially anylocation, substantially obviating the problem of interferring reactionsoccurring with other components of the photosensitive element. When theprocessing composition is applied to the film unit subsequent toexposure, the auxiliary developer is regenerated and able-to function asintended.

The preferred precursors are the alkyl esters and the haloalkyl esters,more preferably the monohaloacetate of the specified auxiliarydeveloper. Thus, the preferred precursors are compounds o f t heformulae:

The alkaline processing composition readily removes the haloacetategroup regenerating the hydroxyl to provide the hydroquinone.

The aforementioned preferred precursors are readily prepared by reactionthe specific hydroquinone with an alkyl anhydride or a monohaloalkylanhydride at elevated temperatures.

In -a particularly preferred embodiment, it has been found that superiorresults are obtained if the auxiliary developers of the presentinvention are employed with precursor of the present'invention.

EXAMPLE Ten grams each of 2,6-di-t-butyl hydroquinone andmonochloroacetic anhydride were mixed and placed ina round bottom flaskfitted with a condenser and a drying tube. The mixture was heated withstirring to 80 C.

for 5 hours. The resulting oil is cooled'and placed into 200 ml. ofwater and stirred until the oil solidifies. The solid is dissolved in200 cc. of methanol and precipitated with 300 cc. of water. Theprecipitate is filtered and washed with water. After drying, the productis recrystallized from hexane to produce the monochloroacetatederivative of 2,6-di-t-butyl hydroquinone melting at 68-69 C. Analysisconfirmed the structure.

The silver halide photosensitive layers employed for the fabrication ofthe photographic film unit, may be prepared by reacting a water-solublesilver salt, such as silver nitrate, with at least one water solublehalide, such as ammonium, potassium or sodium chloride, together withcorresponding iodide and bromide, in an aqueous solution of a peptizingagent such as colloidal gelatin solution; digesting the dispersion at anelevated temperature, to provide increased crystal growth; washing theresultant dispersion to remove undesirable reaction products andresidual water-soluble salts, for example, employing the preferredgelatin matrix material, by chilling the dispersion, noodling the setdispersion, and washing the noodles with cold water, or, alternatively,employing any of the various flocc systems, or procedures, adapted toeffect removal of undesired components, for example, the proceduresdescribed in U.S. Pat. Nos. 2,614,928; 2,614,929; 2,728,662, and thelike; afterripening the dispersion at an elevated temperature incombination with the addition of gelatin or such other polymericmaterial as may be desired and various adjuncts, for example, chemicalsensitizing agents of U.S. Pat. Nos. 1,574,944; 1,623,499; 2,410,689;2,597,856; 2,597,915; 2,487,850; 2,518,698; 2,521,926; and the like; allaccording to the traditional procedures of the art, as described inNeblette, C. B., Photography Its Materials and Processes, 6th Ed., 1962.

Optical sensitization of the emulsions silver iodochlorobromide crystalsmay be accomplished by contact of the emulsion composition with aneffective concentration of the selected optical sensitizing dyesdissolved in an appropriate dispersing solvent such as methanol,ethanol, acetone, water, and the like; all according to the traditionalprocedures of the art, as described in Hammer, F. M., The Cyanine Dyesand Relaled Compounds.

Additional optional additives, such as coating aids, hardeners,viscosity-increasing agents, stabilizers, preservatives, and the like,for example, those set forth hereinafter, also may be incorporated inthe emulsion formulation, according to the conventional procedures knownin the photographic emulsion manufacturing art.

As the binder for the photoresponsive material, the aforementionedgelatin may be, in whole or in part, replaced with some natural and/orsynthetic processing composition permeable polymeric material such asalbumin; casein; or zein or resins such as cellulose derivative, asdescribed in U.S. Pat. Nos. 2,322,085 and 2,541,474; vinyl polymericsuch as described in an extensive multiplicity of readily available U.S.and foreign patents or the photoresponsive material may be presentsubstantially free of interstitial binding agent as described in U.S.Pat. Nos. 2,945,771; 3,145,566; 3,142,567; Newman, Comment onNon-Gelatin Film, B. J. O. P., 434, Sept. 15, 1961; and Belgian Pat.Nos. 642,557 and 642,558..

As previously mentioned, photosensitive silver iodochlorobromideemulsions possessing the preformed grain size distribution may bereadily obtained by a plurality of conventional emulsion manufacturingprocedures known to those skilled in the art, including procedures andapparatus particularly adapted to provide re stricted and substantiallyhomogeneous or uniform grain size distributions; see, for example, theprocesses and apparatus disclosed in U.S. Pat. Nos. 3,326,641 and3,415,650, each of which is specifically hereby incorporated herein byreference.

Reference is now made to FIGS. 1 through 7 of the drawings wherein thereis illustrated a preferred film unit of the present invention andwherein like numbers,

appearing in the various figures, refer to like components.

As illustrated in the drawings, FIG. 1 sets forth a perspective view ofthe film unit, designated 10, and each of FIGS. 2 through 7 illustratediagrammatic crosssectional views of film unit 10, along the statedsection lines 2-2, 33, 5-5 and 7-7, during the various depicted stagesin the performance of a photographic diffusion transfer process asdetailed hereinafter.

Film unit 10 comprises rupturable container 11, retaining, prior toprocessing, aqueous processing composition 12, and photosensitivelaminate 13 including, in order, dimensionally stable opaque layer 14,preferably an actinic radiation-opaque flexible sheet material;

cyan dye developer layer 15; red-sensitive silver iodochlorobromideemulsion layer 16; interlayer 17; magenta dye developer layer 18;green-sensitive silver iodochlorobromide emulsion layer 19; interlayer20; yellow dye developer layer 21; blue-sensitive silveriodochlorobromide emulsion layer 22; auxiliary layer 23, which maycontain an auxiliary silver halide developing agent; image-receivinglayer 24; spacer layer 25;

I neutralizing layer 26; and dimensionally stable trans- .parent layer27, preferably an actinic radiation transmissive flexible sheetmaterial.

The structural integrity of laminate 13 may be maintained, at least inpart, by the adhesive capacity exhibited between the various layerscomprising the laminate at their opposed surfaces. However, the adhesivecapacity exhibited at an interface intermediate imagereceiving layer 24and the silver iodochlorobromide emulsion layer next adjacent thereto,for example, iniage-receiving layer 24 and auxiliary layer 23 asillustrated in FIGS. 2 through 7, should be less than that exhibited atthe interface between the opposed surfaces of the remainder of thelayers forming the laminate, in order to facilitate distribution ofprocessing'solution 12 intermediate the stated image-receiving layer 24and the silver iodochlorobromide emulsion layer next adjacent thereto.The laminates structural integrity may also be enhanced or provided, inwhole or in part, by providing a binding member extending around, forexample, the edges of laminate l3, and maintaining the layers comprisingthe laminate intact, except at the interface between layers 23 and 24during distribution of processing composition 12 intermediate thoselayers. As illustrated in the figures, the binding member may comprise apressure-sensitive tape 28 securing and/or maintaining the layers oflaminate 13 together at its respective edges. Tape 28 will also act tomaintain processing solution 12 intermediate image-receiving layer 24and the silver iodochlorobromide emulsion layer next adjacent thereto,upon application of compressive pressure to pod 11 and distribution ofits contents intermediate the stated layers. Under such circumstances,binder tape 28 will act to prevent leakage of fluid processingcomposition from the film units laminate during and subsequent tophotographic processing.

Rupturable container 11 may be of the type shown and described in any ofUS. Pat. Nos. 2,543,181; 2,634,886; 3,653,732; 2,723,051; 3,056,492;3,056,491; 3,152,515; and the like. In general, such containers willcomprise a rectangular blank of fluidand air-impervious sheet materialfolded longitudinally upon itself to form two walls 29 which are sealedto one another along their longitudinal and end margins to form a cavityin which processing composition 12 is retained. The longitudinalmarginal seal 30 is made weaker than the end seals 31 so as to becomeunsealed in response to the hydraulic pressure generated within thefluid contents 12 of the container by the application of compressivepressure to walls 29 of the container.

As illustrated in FIGS. 1, 2 and 3, container 11 is fixedly positionedand extends transverse a leading edge of photosensitive laminate 13whereby to effect unidirectional discharge of the containers contents 12between image-receiving layer 24 and the stated layer next adjacentthereto, upon application of compressive force to container 11. Thus,container 11, as illustrated in FIG. 2, is fixedly positioned andextends transverse a leading edge of laminate 13 with its longitudinalmarginal seal 30 directed toward the interface between image-receivinglayer 24 and auxiliary layer 23. As shown in FlGS. l, 2 and 4, container11 is fixedly secured to laminate 13 by extension 32 of tape 28extending over a portion of one wall 29 of the container, in combinationwith a separate retaining member such as illustrated retaining tape 33extending over a portion of laminate l3s surface generally equal in areato about that covered by tape 28.

As illustrated in FIGS. 1, 2 and 4, extension flap 32 of tape 28 ispreferably of such area and dimensions that upon, for example, manualseparation of container 11 and tape 33, subsequent to distribution ofprocessing composition 12, from the remainder of film unit 10, flap 32may be folded over the edge of laminate 13, previously covered by tape33, in order to facilitate maintenance of the laminates structuralintegrity, for example, during the flexations inevitable in storage anduse of the processed film unit, and to provide a suitable mask or frame,for viewing of the transfer image through the picture viewing area oftransparent layer The fluid contents of the container preferablycomprise an aqueous alkaline solution having a pH and solventconcentration at which the dye developers are soluble and difiusible andcontains inorganic lightreflecting pigment and at least one opticalfilter agent at a pH above the pKa of such agent in a quantitysufficient, upon distribution, effective to provide a layer exhibitingoptical transmission density about 6.0 and optical reflection densityabout 1.0 to prevent exposure of photosensitive silver iodochlorobromideemulsion layersl6, l9 and 22 by actinic radiation incident ondimensionally stable transparent layer 27 during processing in thepresence of such radiation and to afford, immediate viewing of dye imageformation in image-receiving layer 24 during and subsequent to dyetransfer image formation. Accordingly, the film unit may be processed,subsequent to distribution of the composition, in the presence of suchradiation, in view of the fact that the silver iodochlorobromideemulsion or emulsions of laminate are appropriately protected byincident radiation, at one major surface of the opaque processingcomposition and at the remaining major surface by the dimensionallystable opaque layer. If the illustrated binder tapes are also opaque,edge leakage of actinic radiation incident on the emulsion or emulsionswill also be prevented.

The selected reflecting pigment should be one providing a backgroundsuitable for viewing the dye developer transfer image formed in thedyeable polymeric layer. in general, while substantially any reflectingagent may be employed, it is preferred that a reflecting agent beselected that will not interfere with the color integrity of the dyetransfer image, as viewed by the observer, and, most preferably, anagent which is aesthetically pleasing to the viewer and does not providea background noise signal degrading, or detracting from, the informationcontent of the image. Particularly desirable reflecting agents Will bethose providing a white background, for viewing the transfer image, andspecifically those conventionally employed to provide background forreflection photographic prints and, especially those agents possessingthe optical properties desired for reflection of incident radiation.

As examples of reflecting pigments adapted for employment in thepractice of the present invention, mention may be made of bariumsulfate, zinc sulfide, titanium dioxide, barium stearate, silver flake,silicates, alumina, zirconium oxide, zirconium acetyl acetate, sodiumzirconium sulfate, kaolin, mica, and the like.

A particularly preferred reflecting agent comprises titanium dioxide dueto its highly effective reflection properties. In general, in suchpreferred embodiment, based upon percent titanium dioxide(weight/volume) a processing composition containing about 1500 to 4000mgs./ft. titanium dioxide dispersed in 100 cc. of water will provide apercent reflectance of about to percent. In the most preferredembodiments, the percent reflectance particularly desired will be in theorder of about 85 percent.

In embodiments wherein the dispersion comprises a preformed layerpositioned intermediate the reception layer and next adjacent silveriodochlorobromide layer, the pigment layer will be sufficientlytransparent to allow transit of exposing radiation through the pigmentlayer and may comprise titanium dioxide reflecting agent possessing aparticle size distribution averaging about 0.2 u in diameter andpreferably about 0.05

p. in diameter as initially present preceding exposure of the film unit,which preferred materials, upon contact with aqueous alkaline processingcomposition, preferably aggregate to provide particles possessing adiameter about 0.2 p. in diameter and will be coated at a coverage ofabout 200 to 1000 mgs./ft. Specifically, the reflecting agent will bepresent in a quantity insufficient to prevent exposure of the emulsionlayers by actinic radiation incident on the dimensionally stabletransparent layer of the film unit but in a concentration sufficient,subsequent to processing, to mask dye developer associated with thesilver iodochlorobromide emulsion strata from the dye transfer image. Inthe preferred construction of such embodiment, the pigment such astitanium dioxide will be initially present in a relatively smallparticle size to provide unexpectedly efficient transit of radiationthrough the reflecting layer during exposure which upon contact with analkaline processing composition and aggregation of the pigment particlesprovides efficient light reflectivity and masking capacity subsequent tosuch aggregation.

In general, the reflecting agents to be employed are those which remainsubstantially immobile within their respective compositions during andsubsequent to photographic processing and particularly those whichcomprise insoluble and nondiffusible inorganic pigment dispersionswithin the layer in which they are disposed.

Where desired, reflecting agent pigment may thus be distributed in wholeor in part within a processing composition permeable polymeric matrixsuch as gelatin and/or any other such polymeric matrixes as arespecifically denoted throughout the specification as suitable foremployment as a matrix binder and may be distributed in one or more ofthe film unit layers which may be separated or contiguous, intermediatethe imagereceiving layer and next adjacent silver halide layer, providedthat its distribution and concentration is effective to provide thedenoted post processing masking function, and/or in whole or in part thereflecting agent may be ultimately disposed within the processingcomposition residuum located intermediate the imagereceiving layer andnext adjacent silver halide emulsion strata and associated dyeimage-forming material.

The optical filter agent selected should be one exhibiting, at a pHabove its pKa, maximum spectral absorption of radiation at thewavelengths to which the film units photosensitive silver halide layeror layers are sensitive and should be substantially immobile ornondiffusible within the pigment dispersion, during performance of itsradiation filtration function, in order to maintain and enhance theoptical integrity of the dispersion as a radiation filter unitfunctioning in'accordance with the present invention, and to prevent itsdiffusion into and localized concentration within the image-receivinglayer thereby decreasing the efficiency of the reflecting pigmentdispersion as a background against which image formation may beimmediately viewed, during the initial stages in the diffusion transferprocessing of the film unit, by filter agent absorption of dispersionreflected visible radiation prior to reduction in the environmental pHbelow the pKa of the agent. Commensurate with the spectral sensitivityrange of the associated silver halide layer or layers, the opticalfilter agent selected may comprise one or more filter dyes possessingabsorption complementary to such silver iodochlorobromide layers inorder to provide effective protection against physical fog providingradiation during processing. Recognizing that the filter agentabsorption will derogate from image-viewing characteristics bycontaminating reflecting pigment background, the selected agents shouldbe those exhibiting major spectral absorption at the pH at whichprocessing is effected and minimal absorption at a pH below that whichobtains during transfer image formation. Accordingly, the selectedoptical filter agent or agents should possess a pKa below that of theprocessing pH and above that of the environmental pH subsequenttotransfer image formation, and will be preferably selected for employmentin the minimum concentration necessary to provide an opticaltransmission density about 6.0, at wavelengths at which the silver iodochlorobromide layer is maximally responsive, and an optical reflectiondensity about 1.0 at such wavelengths.

Asspecific examples of such pH-sensitive optical filter agents adaptedfor employment in the practice of the present invention, reference isdirected to the agents set forth in aforementioned copending US. Pat.application Ser. No. 43,782, filed June 5, 1970, incorporated herein byreference.

In general, preferred agents, both opacifying and filter, are thosewhich remain immobile within their respective compositions during andsubsequent to photographic processing and particularly those whichcomprise insoluble and nondiffusible materials.

As disclosed in the previously cited patents, the liquid processingcomposition referred to for effecting multicolor diffusion transferprocesses comprises at least an aqueous solution of an alkalinematerial, for example, diethylamine, sodium hydroxide or sodiumcarbonate and the like, and preferably possessing a pH in excess of 12,and most preferably includes a viscosity-increasing compoundconstituting a film-forming material of the type which, when thecomposition is spread and dried, forms a relatively firm and'relativelystable film. The preferred film-forming materials disclosed comprisehigh molecular weight polymers such as polymeric, water-soluble etherswhich are inert to an alkaline solution such as, forexample, ahydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally,film-forming materials or thickening agents whose ability to increaseviscosity is substantially unaffected if left in solution for a longperiod of time are also disclosed to be capable of utilization. Asstated, the filmforming material is preferably contained in theprocessing composition in such suitable quantities as to impart to thecomposition a viscosity in excess of cps. at

atemperature of approximately 24 C. and preferably in the order of100,000 cps. to 200,000 cps. at that temperature.

In the performance of a diffusion transfer multicolor processemployingfilm unit 10, the unit is exposed to radiation, actinic tophotosensitive laminate l3, incident on the laminates exposure surface,as illustrated in FIG. 3.

Subsequent to exposure, as illustrated by FIGS. 2 and 4, film unit 10 isprocessed by being passed through opposed suitably gapped rolls 35 inorder to apply compressive pressure to frangible container 11 and toeffect rupture of longitudinal seal 30 and distribution of alkalineprocessing composition 12, possessing inorganic light-reflecting pigmentand optical filter agent at a pH above the pKa of the filter agent and apH at which the cyan, magenta and yellow dye developers are soluble 13and diffusible as a function of the point-to-point degree of exposure ofred-sensitive silver iodochlorobromide emulsion layer 16,green-sensitive silver iodochlorobromide emulsion layer 19 andblue-sensitive silver iodochlorobromide emulsion layer 22, respectively,intermediate image-receiving layer 24 and auxiliary layer 23.

Alkaline processing composition 12 permeates emulsion layers 16, 19 and22 to initiate development of the latent images contained in therespective emulsions. The cyan, magenta and yellow dye developers, oflayers 15, 18 and 21, are immobilized, as a function of the developmentof their respective associated silver iodochlorobromide emulsions,preferably'substantially as a result of their conversion from thereduced form to their relatively insoluble and nondiffusible oxidizedform, thereby providing imagewise distributions of mobile, soluble anddiffusible cyan, magenta and yellow dye developer, as a function of thepoint-to-point degree of their associated emulsions exposure. At leastpart of the imagewise distributions of mobile cyan, magenta and yellowdye developer transfers, by diffusion, to dyeable polymeric layer 24 toprovide a multicolor dye transfer image to that layer which is viewableagainst the background provided by the reflecting-pigment present inprocessing composition residuum l2 masking cyan, magenta and yellow dyedeveloper remaining associated with blue-sensitive emulsion layer.

22, green-sensitive emulsion layer 19 and red-sensitive emulsion layer16. Subsequent to substantial transfer image formation, a sufficientportion of the ions comprising aqueous alkaline processing composition12 transfer, by diffusion, through permeable polymeric reception layer24, permeable spacer layer 25 to polymeric neutralizing layer 26 wherebythe environmental pH of the system decreases as a function ofneutralization to a pH at which the cyan, magenta and yellow dyedevelopers, in the reduced form, are substantially nondiffusible tothereby provide a stable multicolor dye transfer image and discharge ofthe pH-sensitive optical filter agent by reduction of the pHsubstantially below the pKa of such agent to thereby provide maximum refflectivity in terms of the pigment concentration presem.

The alkaline solution component of the processing composition,positioned intermediate the photosensitive element and theimage-receiving layer, thus permeates the emulsions to initiatedevelopmentof the latent images contained therein. The respectiveassociated dye developers are mobilized in unexposed areas as aconsequence of the development of the latent images. This mobilizationis apparently, at least in part, due to a change in the solubilitycharacteristics of dye developer upon oxidation and especially asregards its solubility in alkaline solutions. It may also be due in partto a tanning effect on the emulsion by oxidized developing agent, and inpart to a localized exhaustion of alkali as a result of development. Inunexposed and partially exposed areas of the emulsions, the associateddye developer is diffusible and thus provides an imagewise distri butionof unoxidized dye developer dissolved in the liquid processingcomposition, as a function of the pointto-point degree of exposure ofthe silver iodochlo'robromide emulsion. At least part of this imagewisedistribution of unoxidized dye developer is transferred, by imbibition,to a superposed image-receiving layer or lqmenttsa transfstsy inlalxsxclgdin Oxid zed dye developer. The image-receiving elementi'eceivesa depthwise diffusion, from the developed emulsion, of unoxidized dyedeveloper without appreciably disturbing theimagewise' distributionthereof to provide the reversed or positive color image of the developedimage.

Subsequent to distribution of processing composition 12, container 11may be manually dissociated from the remainder of the film unit, asdescribed above, to provide the product illustrated in FIG. 6.

The present invention will be further illustrated and detailed inconjunction with the following illustrative constructions which set outrepresentative embodiments and photographic utilization of the novelphotographic film units of this invention, which, however, are notlimited to the details therein set forth and are intended to beillustrative only.

Film units similar to those shown in the drawings may be prepared, forexample, by coating, in succession, on a 5 mil. opaque polyester filmbase, the following laydispersed in gelatin and coated at a coverage ofabout mgs./ft. of dye and about mgslft. of gelatin;

2. a red-sensitive gelatino-silver iodochlorobromide emulsion coated ata coverage of about I40 mgs./ft. of silver and about 62 mgs./ft. ofgelatin;

3. a layer of butyl acrylate/diacetone acrylamide/styrene/methacrylicacid (60/30/4/6) and polyacrylamide coated in a ratio of about 32:1,respectively, at a coverage of about mgs./ft.

4. a layer of the magenta dye developer HO-CHt-CH;

N-sm- N=N '[-oHi HO-CHr-C 1 L Cr-BhO C lLCH..CH

dispersed in gelatin and coated at acoverage of about i l mgs./ft. ofdye and about 100 'mgs./ft. of gelatin;

minim and the. auxiliary developer 4,-methylphenylhydroquinone dispersedin gelatin and coated at a coverage of about 70 mgs./ft. of dye and 54rn gs./ft. of gelatin;

8. a blue-sensitive gelatino-silver iodochlorobromide emulsion coated ata coverage of about 120 mgs/ft. of silver, about 75 mgs./ft." ofgelatin, and 30 mgs./ft." of auxiliary developer; and

9. a layer of gelatin coated at a level of about 40 mgs./ft.

Then a transparent 5 mil. polyester film base may be coated, insuccession, with the following illustrative layers:

1. a 7:3 mixture, by weight, of polyethylene/maleic acid copolymer andpolyvinyl alcohol at a coverage of about 1400 mgs./ft. to provide apolymeric acid layer;

'2. a copolymer of n-butyl acrylate, styrene, methacrylic acid anddiacetone acrylamide in a weight ratio of 60:4:6z30 at a coverage ofabout 500 mgs./ft. to provide a polymeric spacer layer; and

3. a 2:1 mixture, by weight, of polyvinyl alcohol and comprising:

Water [00.0 cc. Potassium hydroxide 7.5 gms. Carboxymethyl cellulosesodium salt 3.40 gms. N phenethyl-a-picolinium bromide 1.72 gms. Cesiumhydroxide 4.7 gms.

Benzotriazole 1.0 gms.

6-bromo-5-methyl-4 azabenzimidazole 0.05 gms. Titanium dioxide 50.0 gms.Z-methylimidazole 0.35 gms.

may then be fixedly mounted on the leading edge of each of thelaminates, by pressure-sensitive tapes interconnecting the respectivecontainers and laminates, such that,-upon application of compressivepressure to a container, its contents may be distributed, upon ruptureof the containers marginal seal, between the polymeric image-receivinglayer and next adjacent layer.

Theauxiliary developer of the present invention maybe disposed in one ormore of the above emulsion layers, dey developer layers or in theprocessing solution at levels previously designated.

The photosensitive composite film units may be exposed to radiationincident on the transparent polyester layer through a conventional stepwedge and processed by passage of the exposed film units throughappropriate pressure-applying members, such as suitably gapped, opposedrolls, to effect rupture of the container and distribution of itscontents. Subsequent to processing, the multicolor dye transfer imageforma tion may be viewed through the transparent polyester layer againstthe titanium dioxide background provided by distribution of the pigmentcontaining processing composition between layer 9 and the polymericimagereceiving layer.

The following non-limiting'examples illustrate the employment of theauxiliary developers of the present invention in monochromatic filmunits.

2,6-di-t-butyl hydroquinone was tested at various levels in monochromefilm units and processed as described above.

EXAMPLE n A 5 mil. opaque polyester film support was coated,

in order, with 50 mgs/ft. of the above-indicated magenta dye developerdispersed in 750 mgs./ft. of gelatin and 7.5 mgsjft. of4-methylphenylhydroquinone; a green-sensitive gelatin-silveriodochlorobromide emulsion coated at a level of about 150 mgs./ft. ofsilver and 150 mgs./ft. of gelatin; and a gelatin layer coated at alevel of about 30 mgs./ft. 2,6-di-t-butyl hydroquinone was disposed inthe emulsion layer as a solid dispersion. The film unit was exposed andprocessed and the relative speed determined from. an H & D curve.

CONTROL mgsJft. 2,6-di-t-butyl hydroquinone 0 Relative speed EXAMPLE IIIA film unit was prepared by coating a 5 mil. opaque polyester film basewith 50 mg s./ft. of the aboveand 7.5 mgsjft. of4'-methylphenylhydroquinone; and,

a gelatin layer coated at a level of 30 mgs./ft. of 2,6dit-butylhydroquinone was disposed in the emulsion layer at various levels as asolid dispersion. The film unit was exposed and processed and the speeddeter- 1O mined from and H & D curve.

EXAMPLE VI A film unit was prepared by coating a 5 mil. opaque polyesterfilm base with 70 mgs/ft. of the aboveindicated yellow dye developerdispersed in gelatin at a level of about 70 mgsjft. of dye and about 70mgs./ft." of gelatin, a blue-sensitive gelatin-silver iodochlorobromideemulsion coated at a coverage of about 65 mgs./ft. of silver and about50 mgs./ft. of gelatin and 7.5 mgs/ft. of 4-methylphenylhydroquinone;and a gelatin layer coated at a level of 30 mgs./ft. of 2,6-di- CONTROLt-butyl hydroquinone chloroacetate ester was disposed In e m z 6. -t. uin the emulsion layer at various levels as an oil dispery qq 8- g- 15sion. The film unit was exposed and processed and the dame spec I 0speed determined from and H & D curve.

CONTROL mgsjft. 2,6-di-t-butyl hydroquinone chlor0- v acetate ester 00.64 1.28 1.92 2 .56 3.20 Relative speed 100 I05 114 122 124 126 EXAMPLEIV EXAMPLE VI] A 5 mil. opaque polyester support was coated with 100 mgs./ft. of the cyan dye developer indicated above and 92 rngs/ft. ofgelatin; a red-sensitive gelatin-silver iodochlorobromide emulsioncoated at a level of about 140 mgs./ft. of silver and 27 mgsjft. ofgelatin; and a layer of gelatin coated at 30 mgs./ft. The 2,6-di-tbutylhydroquinone chloroacetate ester was disposed in the emulsion layer asan oil dispersion. The film unit was exposed and processed and the speeddetermined on an H & D curve.

CONTROL From the foregoing it will be noted that a speed increase isnoted at various levels with both the auxiliary mgsJfl. 2.6-di-t=butyl vdeveloper per se and with the precursor of the devela fP g g- 2- oper.Similar results may be achieved with 2,5-di-te Spec butyl hydroquinone,durohydroquinone and their precursors. EXAMPLE V 50 The pH and solventconcentration of the alkaline A 5 i] opaque polyester fil Support wascoated, processing solution initially employed will possess a pH inorder, with mgs./ft. of the above-indicated maabove the P of the ophcalfilter agents Where. the genta dye developerdispersed'in 50 mgs./ft. ofgelatin tel are p y d, that. is, the P at which about 50 P and 7.5mgs./ft. 4'-methylphenylhydroquinone; a cent of the agents are presentas the lesser absorbing green-sensitive gelatin-silver iodochlorobromideemul- 55 p ies an about 50 percent are present as the greater sioncoated at a level of about mgs./ft. of silverand absorbing p p a y, 8 Pof about 1 1 and 40 mgs./ft. of gelatin; and a gelatin layer coated at am pref rably about 12 and a pH at which the dye level of about 30mgs./ft. The 2,6-di-t-butylhydroquidevelopers p y are Soluble anddiffusihlenone c'hloroacetate ester was dispersed in the emulsion t ought has been found that the specific pH to be emlayer as an oildispersion. The film unit was exposed 60 ployed maybe'readily determinedempirically for any and processed and the speed determined from an H &dye developer and optical filter agent, or group of dye D curvdevelopers and filter agents, most particularly desirable CONTROLmgSJfL' 2,6-di-t-butyl hydroquinone chloroacetate ester 0 0.64 7.28 1.922.56 3.20 Relative speed I14 100 127 136 142 dye developers are solubleat pHs above 9 and relatively insoluble at pHs below 9, in reduced form,and relatively insoluble at substantially any alkaline pH, in oxidizedform, and the system can be readily balanced accordingly for such dyedevelopers. In addition, although as previously noted, the processingcomposition, in the preferred embodiment, will include the statedfilm-forming viscosity-increasing agent, or agents, to facilitatespreading of the composition and to provide maintenance of the spreadcomposition as a structurally stable layer of the laminate, subsequentto distribution, it is not necessary that such agent be employed as acomponent of the composition.

Neutralizing means, for example, a polymeric acid layer of the typediscussed above may be incorporated, as stated, in the film unit of thepresent invention, to provide reduction of the alkalinity of theprocessing solution from a pH above the pKa of the optical filter agentselected at which the dyes are soluble to a pH below the pKa of theagent at which the dyes are substantially nondiffusible, in order toadvantageously further stabilize and optimize reflectivity of the dyetransfer image. In such instance, the neutralizing layer may compriseparticulate acid reacting reagent dispersed within the film unit or apolymer acid layer, for example, a polymeric acid layer approximating0.3 to 1.5 mils. in thickness, positioned intermediate the transparentsupport and image-receiving layer, and/or the opaque support and nextadjacent emulsion/dye unit layer, and the film unit may also contain apolymeric spacer or barrier layer, for example, approximating 0.1 to 0.7mil. in thickness, next adjacent the polymeric acid layer, opposite therespective support layer, as previously described.

Specifically, the film units may employ the presence of a polymeric acidlayer such as, for example, of the type set forth in US. Pat. No.3,362,819 which, most preferably, includes the presence of an inerttiming or spacer layer intermediate the polymeric acid layer carried ona support and the image-receiving layer.

As set forth in the last-mentioned patent, the polymeric acid layer maycomprise polymers which contain acid groups, such as carboxylic acid andsulfonic acid groups, which are capable of forming salts with alkalimetals, such as sodium, potassium etc., or with organic bases,particularly quaternary ammonium bases, such as tetramethyl ammoniumhydroxide, or potentially acid-yielding groups, such as anhydrides orlactones, or other groups which are capable of reacting with basestocapture and retain them. The acid-reacting group is, of course,retained in the polymer layer. In the preferred embodiments disclosed,the polymer contains free carboxy groups and'the transfer processingcomposition employed contains a large concentration of sodium and/orpotassium ions. The acid polymers stated to be most useful arecharacterized by containing free carboxyl groups, being insoluble inwater in the free acid form, and by forming water-soluble sodium and/orpotassium salts. One may also employ polymers containing carboxylic acidanhydride groups, at least some of which preferably have been convertedto free carboxyl groups prior to imbibition. While the most readilyavailable polymeric acids are derivatives of cellulose or of vinylpolymers, polymeric acids from other classes of polymers may be used. Asexamples of specific polymeric acids set forth in the application,mention may be made of dibasic acid half-ester derivatives'of cellulosewhich derivatives contain free carboxyl groups, e.g., cellulose acetatehydrogen phthalate, cellulose acetate hydrogen glutarate, celluloseacetate hydrogen succinate, ethyl cellulose hydrogen succinate, ethylcellulose acetate hydrogen succinate, cellulose acetate hydrogensuccinate hydrogen phthalate; ether and ester derivatives or cellulosemodified with sulfoanhydrides, e.g., with ortho-sulfobenzoic anhydride;polystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogenphthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid,acetals of polyvinyl alcohol with carboxy or sulfo substitutedaldehydes, e.g., o-, m-, or pbenzaldehyde sulfonic acid or carboxylicacid; partial esters of e'thylene/maleic anhydride copolymers; partialesters of methyl-vinyl ether/maleic anhydride 'copolymers; etc.

As previously noted, the pH of the processing composition preferably isof the order of at least 12 to 14 and the pKa of the selected opticalfilter agents will accordingly preferably be in the order of 13 orgreater. The polymer layer is disclosed to contain at least sufficientacid groups to effect a reduction in the pH of the image layer from a pHof about 12 to 14 to a pH of at least 11 or lower at the end of theimbibition period, and preferably to a pH of about 5 to 8 within a shorttime after imbibition, thus requiring, of course, that the action of thepolymeric acid be accurately so controlled as not to interfere witheither development of the negative or image transfer of unoxidized dyedevelopers. For this reason, the pH of the image layer must be kept at afunctional transfer level, for example, 12 to 14 until the dye image hasbeen formed after 'which the pH is reduced very rapidly to a pH belowthat at which dye transfer may be accomplished, for example, at leastabout 1 l and preferably about pH 9 to 10. Un-

oxidized dye developers containing hydroquinonyl developing radicalsdiffuse from the negative to the positive as the sodium or other alkalisalt. The diffusion rate of such dye image-forming components thus is atleast partly a function of the alkali concentration, and it is necessarythat the pH of the image layer remain on the order of, for example, 12to l4 until transfer of the necessary quantity of dye has beenaccomplished. The subsequent pH reduction, in addition to its desirableeffect upon image light stability, serves a highly valuable photographicfunction by substantially terminating further dye transfer.

In order to prevent premature pH reduction during transfer processing,as evidenced, for example, by an undesired reduction in positive imagedensity, the acid groups are disclosed to be so distributed in thepolymer layer that the rate of their availability to the alkali iscontrollable, e.g., as a function of the rate of swelling of the polymerlayer which rate in turn has a direct relationship to the diffusion rateof the alkali ions. The del sired distribution of the acid groups in thepolymer may be effected by mixing acid polymer with a polymer free ofacid groups, or lower in concentration of acid groups, and compatibletherewith, or by using only an acid polymer but selecting one having arelatively lower proportion of acid groups. These embodiments areillustrated, respectively, in the cited copending application, by (a) amixture of cellulose acetate and cellulose acetate hydrogen phthalateand (b) a cellulose acetate hydrogen phthalate polymer having a muchlower percentage of phthayl groups than the first-mentioned celluloseacetate hydrogen phthalate.

It is also there disclosed that the layer containing the polymeric acidmay contain a water-insoluble polymer, preferably a cellulose ester,which acts to control or modulate the rate at which the alkali salt ofthe polymer acid is formed. As examples of cellulose esters contemplatedfor use, mention is made of cellulose acetate, cellulose acetatebutyrate, etc. The particular polymers and combinations of polymersemployed in any given embodiment are, of course, selected so as to haveadequate wet and dry strength and when necessary or desirable, suitablesubcoats are employed to help the various polymeric layers adhere toeach other during storage and use.

The inert spacer layer of the last-mentioned patent, for example, aninert spacer layer comprising polyvinyl alcohol or gelatin, acts to timecontrol the pH reduction by the polymeric acid layer. This timing isdisclosed to be a function of the rate at which the alkali diffusesthrough the inert spacer layer. It is there stated to have been foundthat the pH does not drop until the alkali has passed through the spacerlayer, i.e., the pH is not reduced to any significant extent by the mere'diffusion into the interlayer, but the pH drops quite rapidly once thealkali diffuses through-the spacer layer.

As disclosed in aforementioned U.S. Pat. No. 3,362,819, the presence ofan inert spacer layer was found to be effective in evening out thevarious reaction rates over a wide range of temperatures, for example,by preventing premature pH reduction when imbibition is effected attemperatures above room temperature, for example, at 95 to l F. Byproviding an inert spacer layer, that application discloses that therate at which alkali is available for capture in the polymeric acidlayer becomes a function of the alkali diffusion rates.

However, as disclosed in U.S. Pat. No. 3,455,686 preferably theaforementioned rate at which the cations of the alkaline processingcomposition, i.e., alkali ions. are available for capture in thepolymeric acid layer should be decreased with increasing transferprocessing temperatures in order to provide diffusion transfer colorprocesses relatively independent of positive transfer image variationsover an extended range of ambient temperatures.

Specifically, it is there stated to have been found that the diffusionrate of alkali through a permeable inert polymeric spacer layerincreases with increased processing temperature to the extent, forexample, that at relatively high transfer processing temperatures, thatis, transfer processing temperatures above approximately 80 F., apremature decrease in the pH of the transfer processing compositionoccurs due, at least in part, to the rapid diffusion of alkali from thedye transfer environment and its subsequent neutralization upon contactwith the polymeric acid layer. This was stated to be especially true ofalkali traversing an inert spacer layer possessing permeability toalkali optimized to be effective with the temperature range of optimumtransfer processing. Conversely, at temperatures below the optimumtransfer processing range, for example, tem peratures belowapproximately 40 F., the lastmentioned inert spacer layer was disclosedto provide an effective diffusion barrier timewise preventing effectivetraverse of the inert spacer layer by alkali having temperaturedepressed diffusion rates and to result in maintenance of the transferprocessing environments high pH for such an extended time interval as tofacili tate formation of transfer image stain and its resultant "werestated to generally comprise saturated aliphatic degradation of thepositive transfer images color definition.

It is further stated in the last-mentioned U.S. Pat. No. 3,455,686 tohave been found, however, that if the inert spacer layer of theprint-receiving element is replaced by a spacer layer which comprises apermeable polymeric layer exhibiting permeability inversely de pendenton temperature, that is, a polymeric filmforming material which exhibitsdecreasing permeability to solubilized alkali derived cations such asalkali metal and quaternary ammonium ions under conditions of increasingtemperature, that the positive transfer image defects resultant from theaforementioned overextended pH maintenance and/or premature pH reductionare obviated.

As examples of polymers which were disclosed to exhibit inversetemperature-dependent permeability to alkali, mention may be made of:hydroxypropyl polyvinyl alcohol, polyvinyl methyl ether, polyethyleneoxide, polyvinyl oxazolidone, hydroxypropyl methyl cellulose, isopropylcellulose, partial acetals of polyvinyl alcohol such as partialpolyvinyl butyral, partial polyvinyl formal, partial polyvinyl acetal,partial polyvinyl propional, and the like.

The last-mentioned specified acetals of polyvinyl hydrocarbon chains ofa molecular weight of at least 1000, preferably of about 1000 to 50,000,possessing a degree of acetalation within about 10 to 30 percent, 10 to30 percent, 20 to percent, and 10 to 40 percent, of the polyvinylalcohols theoretical polymeric hydroxy groups, respectively, andincluding mixed acetals where desired.

Where desired, a mixture ofthe polymers may be employed, for example, amixture of hydroxypropyl methyl cellulose and partial polyvinyl butyral.

Employment of the detailed and preferred film units of the presentinvention, according to the herein described color diffusion transferprocess, specifically provides for the production of a highly stabletransfer image accomplished, at least in part, by effectively obviatingthe previously discussed disadvantages of the prior art products andprocesses, by in process adjustment of the environmental processingcomposition solvent and pH concentration from a solvent and pHconcentration at which dye diffusion or transfer is operative to asolvent and pH concentration at which dye transfer is inoperativesubsequent to. substantial transfer image formation. The stable colortransfer image is obtained irrespective of the fact that the'film unitis maintained as an integral laminate unit during exposure, processing,viewing, and storage of the unit. Accordingly, by means of the presentinvention, multicolor transfer images may be provided over an extendedprocessing temperature range which exhibit desired maximum and minimumdye transfer image densi ties; yellow, magenta and cyan dye saturation;red, green and blue hues; and color separation. These unexpectedadvantages are in addition to the manufacturing advantages obtained byreason of the present inventions integral color transfer film unitconstruction and which will be readily apparent from examination of theunits parameters, that is, for example, advantages in more efficientutilization of fabricating materials and components, enhanced simplicityof film manufacture and camera design and construction, and moresimplified and effectively controlled customer utilization of the unit.

The dimensionally stable support layers referred to may comprise any ofthe various types of conventional opaque and transparent rigid orflexible materials possessing the requisite liquid imperme'ability and,preferably, the vapor transmissivity denoted above, may comprisepolymeric films of both synthetic types and those derived from naturallyoccurring products. Particularly suitable materials include aqueousalkaline solution impermeable, water vapor permeable, flexible polymericmaterials such as vapor permeable polymeric films derived from ethyleneglycol terephthalic acid, vinyl chloride polymers; polyvinyl acetate;polyamides; polymethacrylic acid methyl and ethyl esters; cellulosederivatives such as cellulose, acetate, triacetate, nitrate, propionate,butyrate, acetate-propionate, or acetatebutyrate; alkaline solutionimpermeable, water vapor permeable papers; crosslinked polyvinylalcohol; regenerated cellulose; and the like.

As examples of materials, for use as the imagereceiving layer, mentionmay be made of solution dyeable polymers such as nylon as, for example,N-

methoxymethyl polyhexamethylene adipamide; partially hydrolyzedpolyvinyl acetate; polyvinyl alcohol with or without plasticizers;cellulose acetate with filler as, for example, one-half celluloseacetate and one-half oleic acid; gelatin; and other materials of asimilar nature. Preferred materials comprise polyvinyl alcohol orgelatin containing a dye mordant such as poly-4- vinylpyridine, asdisclosed in U.S. Pat. No. 3,148,061, issued Sept. 8, 1964.

In addition, development may be effected in the presence of an oniumcompound, particularly a quaternary ammonium compound, in accordancewith the processes disclosed in U.S. Pat. No. 3,173,786, issued Mar. 16,1965.

it will be apparent that the relative proportions of the agents of thediffusion transfer processing composition may be altered to suit therequirements of the operator. Thus, it is within the scope of thisinvention to modify the herein described developing compositions by thesubstitution of preservatives, alkalies, etc., other than thosespecifically mentioned, provided that the pH of the composition isinitially atv the first pH and solvent concentration required. Whendesirable, it is also contemplated to include, in the developingcomposition, components such as restrainers, accelerators, etc.Similarly, the concentration of various components may be varied over awide range and when desirable adaptable components may be disposed inthe photosensitive element, prior to exposure, in a separate permeablelayer of the photo-sensitive element and/or in the photosensitiveemulsion.

In all examples of this specification, percentages of components aregiven by weight unless otherwise indicated. I

An extensive compilation of specific dye developers particularly adaptedfor employment in photograhpic diffusion transfer processes is set forthin aforementioned U.S. Pat. No. 2,983,606 and in the various copendingU.S. applications referred to in that patent, es pecially in the tableof U.S. applications incorporated by reference into the patent asdetailed in column 27. As examples of additional U.S. patents detailingspecific dye developers for photographic transfer process use, mentionmay also be made of U.S. Pat. Nos. 2,983,605; 2,992,106; 3,047,386;3,076,808; 3,076,820; 3,077,402; 3,126,280; 3,131,061;

3,134,762; 3,134,765; 3,135,604; 3,135,605; 3,135,606; 3,135,734;3,141,772; 3,142,565; and the like.

As additional examples of synthetic, film-forming, permeable polymersparticularly adapted to retain dispersed dye developer, mention may bemade of nitrocarboxymethyl cellulose, as disclosed in U.S. Pat. No.2,992,104; an acylamidobenzene sulfo ester of a partial sulfobenzal ofpolyvinyl alcohol, as disclosed in U.S. Pat. No. 3,043,692; polymers ofN-alkyl-a, B-unsaturated carboxamides and copolymers ofN-alkyl-a,B-carboxamides with N-hydroxyalkyl-a,/3- unsaturatedcarboxamides, as disclosed in U.S. Pat. No. 3,069,263; copolymers ofvinylphthalimide and a, B-unsaturated carboxylic acids, as disclosed inU.S. Pat. No. 3,061,428; copolymers of N-vinylpyrrolidones anda,/3-unsaturated carboxylic acids and terpolymers ofN-vinylpyrrolidones, a, B-unsaturated carboxylic acids and alkyl estersof a, Bunsaturated carboxylic acids, as disclosed in U.S. Pat. No.3,044,873; copolymers of N,N-dialkyl-a,B-unsaturated carboxamides withafi-unsaturated carboxylic acids, the corresponding amides of suchacids, and copolymers of N-aryland N-cycloalkyl-a,B-unsaturatedcarboxamides with a, fl-unsaturated carboxylic acids, as disclosed inU.S. Pat. No. 3,069,296; and the like.

In addition to conventional techniques for the direct dispersion of aparticulate solid material in a polymeric, or colloidal, matrix such asball-milling and the like techniques, the preparation of the dyedeveloper dispersion may also be obtained by dissolving the dye in anappropriate solvent, or mixture of solvents, and the resultant solutiondistributed in the polymeric binder, with optional subsequent removal ofthe solvent, or solvents, employed, as, for example, by vaporizationwhere the selected solvent, or solvents, possesses a sufficiently lowboiling point or washing where the selected solvent, orsolvents,'possesses a sufficiently high differential solubility in thewash medium, for example, water, when measured against the solubility ofthe remaining composition components, and/or obtained by dissolving boththe polymeric binder and dye in a common solvent.

For further detailed treatment of solvent-distribution systems of thetypes referred to above, and for an extensive compilation of theconventional solvents traditionally employed in the art to effectdistribution of photographic color-providing materials in polymericbinders, specifically for the formation component layers of photographicfilm units, reference may be made to U.S. Pat. Nos. 2,269,158;2,322,027; 2,304,939;.

2,304,940; 2,801,171; and the like.

Although the invention has been discussed in detail throughout employingdye developers, the preferred imageproviding materials, it will bereadily recognized that other, less preferred, image-providing materialsmay be substituted in replacement of the preferred dye developers in thepractice of the invention. For example, there may be employed dyeimage-forming materials such as those disclosed in U.S. Pat. Nos.2,647,049;

2,661,293; 2,698,244; 2,698,798; 2,802,735; 3,148,062; 3,227,550;3,227,551; 3,227,552; 3,227,554; 3,243,294; 3,330,655; 3,347,671;3,352,672; 3,364,022; 3,443,939; 3,443,940; 3,443,941; 3,443,943; etc.,wherein color diffusion transfer processes are described which employcolor coupling techniques comprising, at least in part, reacting one ormore color developing agents and one or more color formers or couplersto provide a dye transfer image to a superposed image-receiving layerand those disclosed in US. Pat. No. 2,774,668 and 3,087,817, whereincolor diffusion transfer processes are described which employ theimagewise differential transfer of complete dyes by the mechanismstherein described to provide a transfer dye image to a contiguousimage-receiving layer, and thus including the employment ofimage-providing materials in whole or in part initially insoluble ornondiffusible as disposed in the film unit which diffuse duringprocessing as a direct or indirect function of exposure.

Although the preceding description of the invention has been couched interms of the preferred photosensitivc component construction wherein atleast two selectively sensitized photosensitive strata are in contiguouscoplanar relationship and, specifically, in terms of the preferredtripack type structure comprising a redsensitive silver halide emulsionstratum, a greensensitive silver halide emulsion stratum and abluesensitive silver halide emulsion stratum having associatedtherewith, respectively a cyan dye developer, a magenta dye developerand a yellow dye developer, the photosensitive component of the filmunit may comprise at least two sets of selectively sensitized minutephotosensitive elements arranged in the form of a photosensitive screenwherein each of the minute photosensitive elements has associatedtherewith, for example, an appropriate dye developer in or behind itsrespective silver halide emulsion portion. In general, a suitablephotosensitive screen will comprise minute red-sensitized emulsionelements, minute greensensitized emulsion elements and minutebluesensitized emulsion elements arranged in side by-side relationshipin a screen pattern and having associated therewith, respectively, acyan, a magenta and a yellow dye developer.

The present invention also includes the employment of a black dyedeveloper and the use of a mixture of dye developers adapted to providea black-and-white transfer image, for example, the employment of dyedevelopers of the three subtractive colors in an appropriate mixture inwhich the quantities of the dye developers are proportioned such thatthe colors combine to provide black.

Where in the specification, the expression positive image has been used,this expression should not be interpreted in a restrictive sense sinceit is used primarily for purposes of illustration, in that it definesthe image produced on the image-carrying layer as being reversed, in thepositive negative sense, with respect to the image in the photosensitiveemulsion layers. As an example of an alternative meaning for positiveimage, assume that the photosensitive element is exposed to actiniclight through a negative transparencey. In this case, the latent imagein the photosensitive emulsion layers will be a positive and the dyeimage produced on the image-carrying layer will be a negative. Theexpression positive image is intended to cover such an image produced onthe image-carrying layer.

It will be recognized that, by reason of the preferred film unit'sstructural parameters, the transfer image formed upon directed exposureof the film unit to a selected subject and processing, will be ageometrically reversed image of the subject. Accordingly, to providetransfer image formation geometrically nonreversed,

exposure of such film unit should be accomplished through animage-reversing optical system such a camera possessing animage-reversing optical system.

In addition to the described essential layers, it will be recognizedthat the film unit may also contain one or more subcoats or layers,which, in turn, may contain one or more additives such as plasticizers,intermediate essential layers for the purpose, for example, of improvingadhesion, and that any one or more of the described layers may comprisea composite of two or more strata of the same, or different, componentsand which may be contiguous, or separated from, each other, for example,two or more neutralizing layers or the like, one of which may bedisposed intermediate the cyan dye image-forming component retaininglayer and the dimensionally stable opaque layer.

Since certain changes may be made in the above product and processwithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:

l. A photographic film unit comprising photosensitive silver halide andan auxiliary silver halide developing agent selected from the groupconsisting of 2,6-di-tbutyl hydroquinone; 2,5-di-tbutyl hydroquinone;durohydroquinone; and the alkyl and haloalkyl ester precursors thereofwherein said silver halide layer has additionally associated therewith adye which has a dihydroxyphenyl silver halide developing function.

2. A product as defined in claim 1 wherein said film unit comprises asupport carrying a photosensitive silver halide layer having associatedtherewith said auxiliary developing agent and said dye.

3. A product as defined in claim 2 wherein said auxiliary developingagent is disposed in a layer adjacent said silver halide layer.

4. A product as defined in claim 2 wherein said auxiliary developingagent is disposed in said silver halide layer.

5. A product as defined in claim 1 wherein said haloalkyl ester is themonochloroacetate ester.

6. A product as defined in claim 1 which includes as a second auxiliarydeveloping agent a hydroquinone silver halide developing agent which issubstantially colorlessat least in its unoxidizedform.

7. A product as defined in claim 6 wherein said hydroquinone silverhalide developing agent is 4- methylphenyl hydroquinone.

8. A product as defined in claim 1 which comprises a plurality of layersincluding a support layer carrying on one surface, in order, a silverhalide emulsion layer having associated therewith a diffusion transferprocess dye image-forming material which has a dihydroxyphenyl silverhalide developing function; an auxiliary silver halide developing agentselected from the group consisting of 2,6-di-t-butyl hydroquinone;2,5-di-tbutyl hydroquinone; durohydroquinone; and the alkyl andhaloalkyl ester precursors thereof; reflecting means adapted to mask dyeimage-forming material associated with said silver halide emulsion layersubsequent to processing of the film unit; and a polymeric layer dyeableby said dye image-forming material.

, comprises, in combination:

a photosensitive element including a composite structure containing asessential layers, in sequence, a first dimensionally stable layer opaqueto incident actinic radiation, a photosensitive silver halide emulsionlayer having associated therewith a diffusion transfer process dyeimage-forming material which has a dihydroxy-phenyl silver halidedeveloping function, and means securing said layers in substantiallyfixed relationship; rupturable container retaining an alkalineprocessing composition containing reflecting agent fixedly positionedand extending transverse a leading edge of said photosensitive elementto effect unidirectional discharge of said containers processingcomposition between said dyeable polymeric layer and the photosensitivesilver halide emulsion layer next adjacent thereto upon application ofcompres sive force to said container; and an auxiliary silver halidedeveloping agent selected from the group consisting of 2,6-di-t-butylhydroquinone; 2,5-di-t-butyl hydroquinone; durohydroquinone; and thealkyl and haloalkyl ester precursors thereof.

10. A product as defined in claim 9 wherein said aux iliary silverhalide developing agent is disposed in said silver halide emulsionlayer.

11. A product as defined in claim 10 wherein said auxiliary silverhalide developing agent is disposed as the haloalkyl ester precursor.

12. A product as defined in claim 9 wherein said auxiliary silver halidedeveloping agent is disposed in said rupturable container.

13. A product as defined in claim 9 wherein said reflecting agent-istitanium dioxide.

14. A product as defined in claim 9 including at least one acid reactingpolymeric layer positioned intermediate at least one of said firstdimensionally stable opaque layers and the photosensitive silver halideemulsion layer next adjacent thereto, and said dimensionally stabletransparent layer and the dyeable polymeric layer next adjacent theretoand said processing composition comprises an aqueous alkaline processingcomposition.

15. A product as defined in claim 14 wherein said polymeric acid layercontains sufficient acidifying function to effect reduction of saidprocessing composition from a first pH at which said dye image-formingmaterial is substantially soluble and diffusible to a second pH at whichsaid image-forming material is substantially nondiffusible.

16. A product as defined in claim 15 wherein said photosensitive elementincludes at least two selectively sensitized silver halideemulsionlayers, each havinga dye of predetermined color associated therewith,which has a dihydroxyphenyl silver halide developing function; each ofsaid dyes soluble and diffusible in alkaline processing composition as afunction of the point-to-point degree of exposure of the respectiveemulsion associated therewith at said first pH and substantiallynon-diffusible in said alkaline processing composition at said secondpH.

17. A process for forming photographic images which includes, incombination, the steps of exposing a photosensitive element comprising aplurality of layers including a support carrying on one surface aphotosensitive silver halide layer, said silver halide layer having adye associated therewith, which has a dihydroxyphenyl silver halidedeveloping function; contacting said photosensitive layer with anaqueous alkaline processing composition and an auxiliary silver halidedeveloping agent selected from the group consisting of 2,6-di-t-butylhydroquinone; 2,5-di-t-butyl hydroquinone; durohydroquinone; and thealkyl and haloalkyl ester precursors thereof for a time sufficient todevelop a latent image in said photosensitive silver halide layer to avisible image.

18. A process as defined in claim 17 wherein said auxiliary developingagent is initially disposed in said aqueous alkaline processingcomposition.

19. A process as defined in claim 17 wherein said auxiliary developingagent is initially associated with said photosensitive element.

20. A process as defined in' claim 19 wherein said auxiliary developingagent is initially disposed in said silver halide layer.

21. A process as defined in claim 20 wherein said auxiliary silverhalide developing agent is initially disposed in said silver halidelayer as said precursor.

22. A process as defined in claim 17 which comprises, in combination,the steps of:

a. exposing a photographic film unit which comprises a plurality oflayers including a photosensitive silver halide layer having associatedtherewith a diffusion transfer process dye image-providing materialwhich has a dihydroxyphenyl silver halide developing function and adiffusion transfer process imagereceiving layer adapted to receivesolubilized image-forming material diffusing thereto;

b. contacting said photosensitive silver halide emulsion with an aqueousalkaline processing composition and an auxiliary silver halidedeveloping agent selected from the group consisting of 2,6-di-t-butylhydroquinone; 2,5-di-t-butyl hydroquinone; durohydroquinone; and thealkyl and haloalkyl ester precursors thereof;

c. effecting thereby substantial development of said silver halideemulsion;

d. forming thereby an imagewise distribution of mobile image-formingmaterial as a function of the point-to-point degree of emulsionexposure; and

e. transferring by diffusion at least a portion of said imagewisedistribution of mobile image-forming material to said layer adapted toreceive said material to provide thereto an image in terms of saidimagewise distribution.

2. A product as defined in claim 1 wherein said film unit comprises asupport carrying a photosensitive silver halide layer having associatedtherewith said auxiliary developing agent and said dye.
 3. A product asdefined in claim 2 wherein said auxiliary developing agent is disposedin a layer adjacent said silver halide layer.
 4. A product as defined inclaim 2 wherein said auxiliary developing agent is disposed in saidsilver halide layer.
 5. A product as defined in claim 1 wherein saidhaloalkyl ester is the monochloroacetate ester.
 6. A product as definedin claim 1 which includes as a second auxiliary developing agent ahydroquinone silver halide developing agent which is substantiallycolorless at least in its unoxidized form.
 7. A product as defined inclaim 6 wherein said hydroquinone silver halide developing agent is4-methylphenyl hydroquinone.
 8. A product as defined in claim 1 whichcomprises a plurality of layers including a support layer carrying onone surface, in order, a silver halide emulsion layer having associatedtherewith a diffusion transfer process dye image-forming material whichhas a dihydroxyphenyl silver halide developing function; an auxiliarysilver halide developing agent selected from the group consisting of2,6-di-t-butyl hydroquinone; 2,5-di-t-butyl hydroquinone;durohydroquinone; and the alkyl and haloalkyl ester precursors thereof;reflecting means adapted to mask dye image-forming material associatedwith said silver halide emulsion layer subsequent to processing of thefilm unit; and a polymeric layer dyeable by said dye image-formingmaterial.
 9. A product as defined in claim 8 which is adapted to beprocessed by passing said member between a pair of juxtaposedpressure-applying members and which comprises, in combination: aphotosensitive element including a composite structure containing asessential layers, in sequence, a first dimensionally stable layer opaqueto incident actinic radiation, a photosensitive silver halide emulsionlayer having associated therewith a diffusion transfer process dyeimage-forming material which has a dihydroxy-phenyl silver halidedeveloping function, and means securing said layers in substantiallyfixed relationship; a rupturable container retaining an alkalineprocessing composition containing reflecting agent fixedly positionedand extending transverse a leading edge of sAid photosensitive elementto effect unidirectional discharge of said container''s processingcomposition between said dyeable polymeric layer and the photosensitivesilver halide emulsion layer next adjacent thereto upon application ofcompressive force to said container; and an auxiliary silver halidedeveloping agent selected from the group consisting of 2,6-di-t-butylhydroquinone; 2,5-di-t-butyl hydroquinone; durohydroquinone; and thealkyl and haloalkyl ester precursors thereof.
 10. A product as definedin claim 9 wherein said auxiliary silver halide developing agent isdisposed in said silver halide emulsion layer.
 11. A product as definedin claim 10 wherein said auxiliary silver halide developing agent isdisposed as the haloalkyl ester precursor.
 12. A product as defined inclaim 9 wherein said auxiliary silver halide developing agent isdisposed in said rupturable container.
 13. A product as defined in claim9 wherein said reflecting agent is titanium dioxide.
 14. A product asdefined in claim 9 including at least one acid reacting polymeric layerpositioned intermediate at least one of said first dimensionally stableopaque layers and the photosensitive silver halide emulsion layer nextadjacent thereto, and said dimensionally stable transparent layer andthe dyeable polymeric layer next adjacent thereto and said processingcomposition comprises an aqueous alkaline processing composition.
 15. Aproduct as defined in claim 14 wherein said polymeric acid layercontains sufficient acidifying function to effect reduction of saidprocessing composition from a first pH at which said dye image-formingmaterial is substantially soluble and diffusible to a second pH at whichsaid image-forming material is substantially nondiffusible.
 16. Aproduct as defined in claim 15 wherein said photosensitive elementincludes at least two selectively sensitized silver halide emulsionlayers, each having a dye of predetermined color associated therewith,which has a dihydroxyphenyl silver halide developing function, each ofsaid dyes soluble and diffusible in alkaline processing composition as afunction of the point-to-point degree of exposure of the respectiveemulsion associated therewith at said first pH and substantiallynon-diffusible in said alkaline processing composition at said secondpH.
 17. A process for forming photographic images which includes, incombination, the steps of exposing a photosensitive element comprising aplurality of layers including a support carrying on one surface aphotosensitive silver halide layer, said silver halide layer having adye associated therewith, which has a dihydroxyphenyl silver halidedeveloping function; contacting said photosensitive layer with anaqueous alkaline processing composition and an auxiliary silver halidedeveloping agent selected from the group consisting of 2,6-di-t-butylhydroquinone; 2,5-di-t-butyl hydroquinone; durohydroquinone; and thealkyl and haloalkyl ester precursors thereof for a time sufficient todevelop a latent image in said photosensitive silver halide layer to avisible image.
 18. A process as defined in claim 17 wherein saidauxiliary developing agent is initially disposed in said aqueousalkaline processing composition.
 19. A process as defined in claim 17wherein said auxiliary developing agent is initially associated withsaid photosensitive element.
 20. A process as defined in claim 19wherein said auxiliary developing agent is initially disposed in saidsilver halide layer.
 21. A process as defined in claim 20 wherein saidauxiliary silver halide developing agent is initially disposed in saidsilver halide layer as said precursor.
 22. A process as defined in claim17 which comprises, in combination, the steps of: a. exposing aphotographic film unit which comprises a plurality of layers including aphotosensitive silver halide layer having associated therewith adiffusion transfer process dye image-Providing material which has adihydroxyphenyl silver halide developing function and a diffusiontransfer process image-receiving layer adapted to receive solubilizedimage-forming material diffusing thereto; b. contacting saidphotosensitive silver halide emulsion with an aqueous alkalineprocessing composition and an auxiliary silver halide developing agentselected from the group consisting of 2,6-di-t-butyl hydroquinone;2,5-di-t-butyl hydroquinone; durohydroquinone; and the alkyl andhaloalkyl ester precursors thereof; c. effecting thereby substantialdevelopment of said silver halide emulsion; d. forming thereby animagewise distribution of mobile image-forming material as a function ofthe point-to-point degree of emulsion exposure; and e. transferring bydiffusion at least a portion of said imagewise distribution of mobileimage-forming material to said layer adapted to receive said material toprovide thereto an image in terms of said imagewise distribution.